This proposal aims at developing a compact label-free biomolecule microarray for personalized and specific diagnostic assays of various cancers and allergies using two-dimensional photonic crystal microcavity devices. Defect engineered photonic crystals, with sub-micron dimensions have already demonstrated high sensitivity to trace volumes of analytes. While biosensing has been demonstrated in these devices with single biomolecules, no previous effort has been made to extend device capability to microarrays. Particularly, patterning of multiple biomolecules on a few micron scales has faced challenges of binding exclusivity and binding specificity. Our device consists of an array of photonic crystal microcavity resonators coupled to a single photonic crystal waveguide that give rise to minima in the photonic crystal waveguide transmission spectrum at the resonance frequency of the microcavity. When a probe biomolecule binds specifically to a target biomolecule, coated exclusively on the microcavity, shift in microcavity resonance translates to corresponding shift in photonic crystal waveguide transmission minimum. The method eliminates labeling for analyte identification. The impact of our novel and robust multi-analyte sensing technique can reach much further than the field of biomolecular science and diagnostics alone. Our research will lead to highly parallel detection of multiple diseases and thus a low-cost personalized diagnostic assay.